High conductivity, phosphorus-deoxidized copper and process for making the same



231 W37, 5 F POLAND 2,,w2fi4l-2 HIGH CONDUCTIVITY, PHOSPHORUS DEOXIDIZED COPPER AND PROCESS FOR MAKING THE SAME Filed March 26, 1935 INVENTOR A'ETORN EY Patented Dec. 21, 1937 oxrmznn corrsn MAKING THE same I 2,102,742 HIGH GONDUCTIVITY,

PHD SPHORUS-DE- AND PROCESS FOR Frank F. Poland,New Brunswick, N. 3., assignor to American smelting and Refining Company, New York, N. Y., a corporation of New Jersey Application March 26, 1035, Serial No. 13,049

i Elaims.

This invention relates to certain improvements in deoxidizing and casting copper and to the copper thereby produced.

The invention provides copper in billet, cake,

wire-bar or other desired commercial shape which, by reason of certain, definite characteristics which it possesses, fulfills many varied industrial demands and is firmly establishing itself in the channels of commerce.

Briefly, the copper of the present invention is a substantially non-porous product of homogeneous, uniform composition having a phosphorus content not exceeding 0.01%. Further, the copper of the invention possesses a higher 5 tensile strength than electrolytic copper, is equal to or superior to electrolytic copper in conductivity, is substantially the same as pure oxygenfree copper as regards elongation, permits of annealment in reducing gases without embrittle- 2011181; and has the ductility and softness of substantially pure copper. The loss of weight for the copper of the invention when heated in hydrogen is substantially the same as that forpxygen-free copper, the total loss of weight exhibited by the new product not exceeding 0.01% and the oxygen content (total loss in weight minus sulphur) being substantially less than 0.01% when heated in hydrogen for one and one-half hours at 850- 900 C. L

This application is a continuation in part of the application of Frank F. Poland, Serial Number 684,630 filed August 11, 1933. forProcess of treating copper.

While copper metallurgists generally have long recognized the deoxi'dizing propertiesof phosphorus, it has also heretofore been commonly believed that copper having certain properties could not be produced by phosphorus deoxidation. Prior to the present invention it was generally re- 40 garded in the art, and even by the present applicant, that approximately 0.015% phosphorus in the product represented the permissible minimum by reason of the porosity and accompanying low electrical conductivity which characterized 4.5 the metal when less phosphorus was present. On the other hand, a lower phosphorus content has long been demanded by fabricators by reason of the fact that in the fabrication of articles substantial amounts of scrap inevitably result which the fabricators desire to use in various alloy manufactures. Hence, ii a high phosphorus content is deleterious in a particular alloy or article, the field of the fabricator in utilizing this scrap is necessarily curtailed.

By providing a copper product which easily Relatively pure copper, for example, cathode copper-or scrap electrolytic copper is melted in a furnace, of the reverberatory or other suitable type having a convenient capacity of 25 tons or upward and the melted charge oxidized byblowing with air to drive off sulphur and dissolved in the copper. L

The bath is covered with a layer of suitable carbonaceous material such as coke or charcoal which is sumciently thick to deoxidize the copper during the poling process and to provide a complete protective the copper is poled to tough pitch and throughout the duration of the casting period In practise, ii paling is halted when the oxygen content is about 0.04% the oxygen content will, in the presence of the above-mentioned layer of carbon, actually decrease to a substantially oxygen-free stage (below 0.01% 02). Y

From the furnace, the copper is poured into a suitable receptacle, for example, a ladle holding from 1000 to 2000 pounds. In the ladle, the copper is covered with a protective carbonaceous layer and reacted with a predetermined amount of copper phosphorus alloy containing a quantity of phosphorus sufiicient to completely deoxidize the copper and to impart thereto a residual phosphorus content "of not more than 0.01%.

In practise, the receptacle or ladle is graduated at the levels to which known weights of copper rise when such weights are poured into same and graduated known weights of the copper phosphorus alloy are provided beforehand so that the quantity of alloy requisite for the proper treatment oi whatever amount of copper is delivered from the furnace 'is immediately available.

While it is possible to employ phosphorus in elemental form, an alloy of phosphorus and copper is very much preferred, particularly the eutectic alloy containing 8.27% phosphorus although other copper phosphorus alloys of which blanket several inches thick after the composition is known can be readily ployed.

Following the deoxidation of the copper and solution of the. phosphorus in the metal which may be facilitated by stirring with a graphite rod, the copper is poured into molds of desired shape which have previously been coated with a thin, continuous film of a prepared mold dressing which effectively prevents or precludes porosity in the product. i

The mold dressing used comprises a resinous solution such as rosin, shellac, copal or the like in a solvent such as alcohol, acetone, etc. to which bone black, bone ash or graphite is preferably incorporated, the preferred dressing consisting of bone black suspended in an alcoholic solution of resin. V

In the accompanying drawing there is illustrated diagrammatically a ladle of the type which may be employed in producing the improved product of the invention.

Referring to the drawing, a shallow ladle of the teapot type is shown having a body portion ii and'spout 52. This ladle is construcwd in a manner well known in the art and, if desired, may be supported on a removable carriage not shown, and adapted to tip for the purpose of pouring the contents through spout it.

In operation, calculated requisite amount of phosphorus in the form of a phosphor-copper alloy containing a known percentage of phos: phorus, as, for example, 15%, indicated in the drawing by i3, is placed in a paper bag, indi cated by it, and the entire bottom of the ladle covered with hot foundry coke or charcoal M. A determined amount of molten tough pitch copper is then introduced through the spout i2. Reference character it indicates the copper in the ladle after the pouring operation just described. a

The ladle i0 may be of such size to hold from 500 to 2000 lbs. and may be so construcmd that the molten copper can be poured into the spout H2 in about fifteen seconds. The agitation caused by the pouring operation causes the phosphorus to combine with the oxygen in the copper to form phosphorus pentoxide (P205) which is a fluid slag at the temperatures used. This slag rises to the top of the metal where it comes in contact with the hot coke or charcoal and is reduced thereby to phosphorus which again enters the metal and goes through the same cycle repeatedly until all of the oxygen in the copper is removed. After deoxidizing the copper, the phosphorus dissolves in the molten copper, the above reaction taking place without any appreciable loss of phosphorus and going on extremely rapidly because of the thorough agitation obtained by pouring the heavy stream of molten metal into the the shallow ladle. The foregoing is, of course, to be considered in an explanatory and not in a limiting sense as it is quite possible that experts may differ in their opinions as to the exact theory of operation.

After the purifying action has taken place, the ladle i0 is tipped to pour the deoxidized copper through the spout i2 into a suitable rnold which has been previously coated with a thin film of a prepared mold dressing as above described. Such dressing may be prepared by dissolving resin in alcohol in amounts varying from onei half pound per gallon to the limit of solubility of the particular resin employed in alcohol, and adding bone black in quantities varying from one-half pound to a quantity sumcient toform a thick paste, the preferable dressing comprising approximately one and one-half pounds of resin and approximately three pounds of bone black per gallon of alcohol.

It has been found in treating copper by the present invention that in addition to readily deoxidizing the copper, the residual phosphorus content thereof may consistently be held within low, narrow limits not exceeding 0.01%, as for example, 0.006% to 0.009%. accurate control the residual phosphorus content and the use of a mold wash of the class described yield new and improved results in producing the irn= proved product described herein. The use of the mold wash of the type described facilitates elimi nation of porosity in the product and makes for soundness thereof. It is believed that when ordinary mold washes such as oils, etc., are used, the oil volatilizes and thereby disturbs the copper crystals thus inhibiting their growth. On the other hand, a moldwash of the class de= scribed reduces the agitation of the crystals and allows them to grow larger, thus yielding a superior product and eliminating porosity.

It has already been indicated that the low phosphorus content of less than 0.01% is highly desirable. In this connection it may be noted that in fabrication, this small amount of phosphorus is beneficial because of the completeness of the removal of all scale from the articles made from the product, during pickling operations. For example, in the fabrication of tubes from round billets, the billets are heated to a neighborhood of 1600 F. and even if the furnace atmosphere be controlled so as not to oxidize the surface of the billets during this heating, the billets will become oxidized during the boring, forming scale. The resulting tube is quenched in Water and then pickled in sulphuric acid. Actual experience shows that very frequently the scale on the surfaces containing no phosphorus is so adherent that it will not be completely removed during pickling and consequently it is necessary to maintain a close inspection of the tubes coming from the pickling operation and to sort out and repickle those that are not completely clean.

However, in the case/of tubes made from the present improved product containing the small amounts of phosphorus above indicated, any scale that is formed is non-adherent and is removed mainly in the quenching bath prior to the pickling, so that there is a complete removal of the scale in the pickling. Thus the product of the invention while not possessing a sufiicient lyhigh phosphorus content to be objectionable to the fabricators, does contain a sufficient amount of that element to insure ready and completeremoval of oxide scale.

The high electrical conductivity of the present improved product has been mentioned. According to the A. S. T. M. specifications, the conductivity of electrolytic copper must be at least 99.3%. This is the minimum conductivity of the present improved product, the conductivity of which ranges up to 101% as measured by the A. S. T. M. specifications. A conductivity is equivalent, on the International annealed copper standard, to a resistivity of 0.15328 International ohm per meter-gram at 20 C., and "High conductivity copper on this standard has a resistivity of not more than 0 ;15436 International ohm per meter-gram at 20 0. Repeated tests of the present product show that its resistivity lies between 0.15436 and 0.15057 International ohm per meter-gram at 20 C. thereby fulfilling all requirements of High conductivity copper.

What is claimed is:

l. The method of treating relatively pure copper which compriseslintroducing same in the molten state into contact with a predetermined amount of phosphor-copper of known composition under a bed of carbonaceous reducing agent thereby deoxidizing the copper and imparting thereto a predetermined phosphorus content and casting the resultant deoxidized copper into a mold of desired shape, the interior surfaces of which are coated with a mold dressing comprising an alcoholic solution of resin in which bone black is suspended.

2. The method of producing copper having high conductivity and ductility which comprises reacting molten tough pitch copper under a blanket of hot coke with an amount of phosphorus-copper alloy of known composition in quantity sufficient to deoxidize the copper and impart thereto a predetermined residual phosphorus content and casting the resultant deoxidiZed copper into a mold previously dressed with an alcoholic solution of resin containing bone black.

3. The method of producing copper having high conductivity and ductility which comprises reacting molten tough 'pitch copper under a blanket of hot coke with an amount of phosphoruscopper alloy of known composition in quantity sufficient to deoxidize the copper and to impart thereto a predetermined residual phosphorus content of 0.01% or less and casting the resultant deoxidized copper into a mold previously dressed with an alcoholic solution of resin containing bone black.

4. The method of producing a deoxidized, nonporous, high conductivity copper product containing less than 0.01% of phosphorus which comprises placing a phosphorus-copper alloy in predetermined amount in a shallow ladle under a blanket of a heated carbonaceous reducing agent, adding molten copper thereto thereby deoxidizing the copper and pouring the deoxidized copper into a mold, the interior of which is coated with a solution of resin in which bone black is suspended.

5. The method of producing a deoxidized nonporous, high conductivity copper product containing not more than 0.01% phosphorus which comprises contacting a predetermined amount of phosphorus-copper alloy with copper in the presence of a protective layer of a carbonaceous re ducing agentjthe phosphorus being present in amounts sufiicient to render the copper oxygenfree and togive a controlled residual phosphorus content of less than 0.01% in the resulting prod- "ciency. of phosphorus the phosphorus-copper to deoxidize the same uct, effecting solution of alloy in the said copper and pouring the deoxidized copper into a mold the interior of which is coated-with a resinous solution containing an inert substance selected from the group comprising bone ash, bone black and graphite.

6. The method of treating copper which comprises deoxidizing same under a layer of carbonaceous material with sufiicient phosphorus to completely deoxidize the copper and impart thereto a residual phosphorus content no greater than 0.01% and casting the deoxidized copper into a mold coated with a resinous solution in which bone ash, bone black or graphite is suspended thereby producing a copper shape which is nonporous, homogeneous and at least equivalent to electrolytic copper in conductivity.

7. The method of producing deoxidizcd, highconductivity copper containing phosphorus but in amounts not more than 0.01%, which comprises melting copper of a purity equivalent to electrolytic copper, converting the molten copper into a substantially oxygen-free condition, and incorporating into the resulting copper a calculated sufliciency of phosphorus to completely deoxidize the copper and to leave a residual phosphorus content of not more than 0.01%.

8. The method of producing a dedxidized highconductivity copper containing phosphorus but in amounts less than 0.01%, which comprises melting copper of a purity equivalent to electrolytic copper, converting the molten copper into a substantially oxygen-free condition and incorporating into the resulting copper sufficient eutectic phosphorus-copper alloy to give a calculated suifito completely deoxidize the copper and to leave a residual phosphorus content of less than 0.01%.

9. A homogeneous, phosphorus-deoxidized copper containing small amounts of residual phosphorus not exceeding 0.01% and substantially less than 0.01% oxygen, the said copper having an electrical resistivity of between 0.15436 and 0.15057 International ohm per meter-gram at 20 C. and possessing the ductility and softness of substantially pure copper.

10. Commercially sound, phosphorus-deoxidized copper having a phosphorus content between the limits of 0.006% and 0.009%, said copper possessing an electrical resistivity not exceeding 0.15436 International ohm per metergram at 20 C. and exhibiting a total loss in weight of less than 0.01% when heated in hydrogen for one and one-half hours at a temperature of 850-900 C.

FRANK F. POLAND. 

